Acoustic device



sept. 12, 1983. R L WEGEL 1,926,888

ACOUSTIC DEVICE Filed Feb. 5I 1924 Patented Sept. J1-"2, 1933 ACOUSTIC DEVICE ERaymond L. Wegel, New York, N. Y., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application February 5,

38 Claims.

y This invention relates to acoustic devices and j particularly to loud speaking receivers employ- 'ing large direct acting diaphragms.

The object of this invention is to provide a compact and rugged loud speaker capable of efficiently and faithfully reproducing all sounds within the audible range.

One feature of the invention provides for the Vvibratory system a light rigid non-resonant protective casing offering minimum interference to the projection of the sound waves. In accordance with this feature, the vibratory system is enclosed in a wicker casing having the general shape of the diaphragm, the front and rear of thecasing being removable to render the vibratory system readily accessible.

Another feature' provides a large direct acting 'conical 'diaphragm formed of a plurality of concentric conic sections having substantially different characteristics of elasticity and density so as tosimulate a diaphragm having uniform -radial distribution of these characteristics. Specifically,- this feature provides a conical diaphragm having a plurality of concentric portions, each of a different ratio of elasticity to mass and having joining edges preferably serrated in order to eliminate any sudden change in going'from one material to the next in the ratio of the elasticity to mass, and thus provide uniform transition of sound Waves along the surface of the diaphragm.

Referring to the drawing; Fig. l is a front view of aloud speaking receiver embodying the invention; Fig. 2 is an exploded cross sectional view; Fig. 3 shows a diaphragm embodying one feature of the invention; Fig. 4 is an enlarged fragmentary view of the diaphragm of Fig. 3; and Fig. 5 Yis a modification of the diaphragm of Figs.3 and 4.

On a base 6 is supported a substantially upright member 7 carrying annular members 8 and 9 and bracket 10. Secured tothe annularmember 9 by screws 12 threaded therein is a ring 11 of substantially the same diameter. Supported on the bracket 10 is a receiver unit 13 preferably Yof the balanced armature type shown in Patent No. 1,365,898 of January 18, 1921, to H. C. Egerton.

A large direct acting double conical diaphragm 15, one side of which is truncated and open, or closed, is secured to the annular member 9 in any suitable manner. To the apex of the conical diaphragm is connected the receiver unit 13 by a rod 14. Y

The casing for the `vibratory system is prefer- 1924. Serial No. 690,695

ably made of Wicker or some such material, and

for convenience is made in three parts, a frame 16, a cover or front 17 and a rear 18. The frame portion 16 is preferably Woven over the rings 8 and l1 leaving a central opening in the rear which is closed by the portion 18 held in place by any suitable means, such as spring clips 19. The basket-like cover 17 is preferably conical in shape and has an inturned edge, the inside diameter of which is slightly smaller than the outside diameter of the ring 8 with its wicker covering. The cover 17 may be readily sprung in place over the ring 8 Where it will be securely but detachably held by its own tension.

The diaphragm 15 is preferably made of two opposed conical vibratory members, one of which is truncated and secured at its inner periphery to the mounting ring 9 thereby providing an opening in the rear of the diaphragm, advantage of which is taken to mount the receiver unit 13' in the interior of the diaphragm in proximity to its apex so that the connecting rod 14 may be made relatively short and light. The vibratory member forming the face of the diaphragm is preferably made with an inserted central portion 22, as shown in Figs. 3, 4, and 5 having edges overlapping the outer portion 2l only sufciently to form a good cemented joint. The central portion 22 is preferably made of a light material such as a good grade of a thin hard paper having a high ratio of elasticity to mass and low internal friction. Since the reproduction of the higher frequencies of small amplitudes depends to a very large extent upon the central portion of the diaphragm, this part should be made as light and as stiff as possible. The outer portion on which the reproduction of the lower frequency vibrations depends is preferably made of material having a lower ratio of elasticity to Y mass and higher internal friction. Blotting paper has been found to be a Very satisfactory material for this portion 21 of the diaphragm and also for the truncated portion 23. The inserted portion 22 may be made of aluminum foil or any of the lighter metals or alloys. Both aluminum and thin hard surface drawing paper have been found tc give very satisfactory results when used for portion 22 of the diaphragm.

Whenever sound Waves travel through air or other conductors having sudden changes in size, shape or material, therer is-more or less wave energy reflected. This is also true in diaphragms having concentric sections of different materials. In order to minimize this reflection loss, the joined edges of adjacent portions may be portant.

deeply serrated to form a zigzag joint thereby insuring gradual transition from one portion to the next. The vibrations oi the rod lei may be transmitted to the diaphragm by a small ainminum conical member 25 disposed on each side ofthe portion 22 and held in place by means of an eyelet 26 extending through both. The members 25 have serrated edges to further inlsure the gradual transition from portion to porto give excellent results. A practicable size however, is one having a diameter of about 18 and an insert approximately 9" in diameter, the insert being made of thin glazed drawing paper and the other'portion of the face and the truncated member of blotting paper. v The actual materials to be used,l however, are not so im- The central portion should be made as light and stii as possible, the lighter and stiffer the better. It may also be formed of a plurality of concentric joined sections of diiferent thicknesses and `elastic-.ities as shown in Figs.'3 and 4., The outer portion 21 shculdbe of lower elasticity and a higherinternal friction so as to attenuate the waves as they approach the outer edge of the diaphragm and minimize reection at this point. As a means for preventing reection, it has also been found advantageous in some to apply a damping element 28 of vibration absorbing material near the periphery of the face of the diaphragm. As shown in the drawing, this element comprises an annular felt ring cemented to the rear of the front portion of the diaphragm.

What is claimed is:

1. An acoustic device comprising a large direct acting diaphragm and a wicker casing therefor,

said casing comprising a conical back, a support therefor, and an opposing conical fac-e.

2. An acoustic diaphragm comprising a standard, a large ring anda substantially smaller concentric ring carried by said standard, an annular member of woven material joining said rings, a non-resonant closure for the opening '1nk said smaller rings, a large `direct acting-diaphragm supported by said smaller ring, and a cover of non-resonant material for said diaphragm detachably engaging said larger ring.

3. In an acoustic device, a large direct acting diaphragm comprising a central portion and a marginal'portion, said central portion having a lower internal friction and lighter mass than said marginal portion.

4. In an acoustic device, a large direct acting diaphragm comprising an annular marginal portion having a serrated inner edge, a central portion having a serrated edge, the serrations of one portion overlapping in staggered relation those of the other portion.V

5. In an acoustic device, a large direct acting diaphragm comprising a plurailty of concentric juxtaposed portions of different elasticitiesV and diameters, the inner portion having a serrated edge, thereby providing substantially uniform transition of vibrations from the inner to the outer portions.

6. In an acoustic device, a large direct acting diaphragm comprising a central portion and an annular outer portion, said central portion of a thin material having high elasticity, and said outer portion of a material having the characteristics of blotting paper.

7. In an acoustic device, a direct acting diaphragm comprising a central portion having the characteristics of drafting paper, and a large outer portion having the characteristics of blotting paper.

8. In an acoustic device, a large direct acting diaphragm comprising a plurality of concentric portions increasing in thickness and decreasing in elasticityv progressively outward.

' 9. An acoustic device comprising a large direct actingv hollow conical diaphragm, a standard supporting said diaphragm, an actuating device disposed within said diaphragm, and a rigid nonresonant non-metallic enclosure for said dlaphragm and said actuating device.

10. An acoustic device comprising a large dlrect acting diaphragm, and damping means solely supported by said diaphragm.

11. An acoustic device comprising a large direct acting diaphragm, and sound absorbing means carried solely by said diaphragm.

12. An acoustic device comprising a" large direct acting 4conical diaphragm, and a felt ring cemented to said diaphragm near the periphery thereof and carried solely thereby.

13. An acoustic device comprising a direct acting diaphragm, an actuating device, means supporting said actuating device in operative relation to said diaphragm, and a ring of sound absorbing material solely supported by said diaphragm. i

14. In an acoustic device, a diaphragm having a mainportion and a juxtaposed central portion having a serrated edge, and means secured to said central portion for actuating said diaphragm.

15. An acoustic device having a large direct acting diaphragm, and an actuating means, said diaphragm comprising a conical main portion and a serrated central conical disc adapted t0 connect said diaphragm to said actuating means.

16. An acoustic device having a large direct acting diaphragm composed of a central portion and a main portion, said central portion having aV serrated edge and a different density'and elasticity than said main portion.

17. An acoustic device comprising a large direct acting conical diaphragm, driving means therefor, a conical-shaped member supporting said diaphragm and forming with said dlaphragm an enclosure for said driving means, a

standard for supporting said member, and a non-resonant non-metallic cover for the front p of said diaphragm.

1S. A conical-shaped diaphragm, a rigid nonmetallic cover for the front of said diaphragm, a standard, and a dish-shaped means for supporting said diaphragm and said cover on said standard.

19. In an acoustic device, a diaphragm having a free vibrating edge and comprising two sections having different masses per unit ot'- area, and means for applying vibrational forces to the section having the lesser mass per unit of area.

20. In an acoustic device, a diaphragm having. the shape of a hollow shell and comprising two sections having different masses per unit of area, and. means for applying vibrational forces to the section having the lesser mass per unit of area.

21. An acoustic device comprising a free edge diaphragm having two sections of different ratios of elasticity to mass per unit of area, and means for applying Vibrational forces to the section having the greater' ratio per unit of area.

22. In an acoustic device, a diaphragm having the form of a hollow shelland comprising two sections of different ratios of elasticity to mass per unit of area, and means for applying vibrational forces to the section having the greater ratio of elasticity to mass per unit of area.

23. An acoustic device comprising a diaphragm having a plurality of sections of different thicknesses and elasticities joined together, the joint between adjacent sections being such as to eifect a gradual change from the thickness and elasticity of one of said adjacent sections to the thickness and elasticity of the other of said adjacent sections so as to minimize reflection losses between sections. l

24. An acoustic device comprising a diaphragm having a plurality of sections of diiierent thicknessesfand elasticities joined together, the joint between adjacent sections being such as to gradually change from the thickness and elasticity of one of the adjacent sections to the thickness and elasticity of the other of the adjacent sections so as to minimize reflection losses between sections, and vibration absorbing means at the outer portion of the diaphragm for reducving reflection losses thereat.

25. A sound reproducer comprising a cone shaped diaphragm, means for imparting sound vibrations to said diaphragm, and a sound vibration damper upon said diaphragm. and ex tending over a portion of the vibratable surface thereof.

26. Arsound reproducer comprising a sound reproducing diaphragm, means for imparting sound vibrations thereto, and a sound vibration damper inthe form of an annular member attached to said diaphragm and extending over a portion of the sound radiating area of said diaphragm remote from the center.

27. A sound reproducer comprising a cone shaped member and an annular member connected to the base of said cone shaped member, and damping means'for said cone shaped member disposed over a portion of its surface between the apex of said cone shaped member and said annular member.

28.A sound reproducer comprising. a cone shaped member and an annular member connected Yto the base of said cone shaped member, and an annular member of fibrous material attached to said cone-shaped member.

29. In a sound reproducer, a conical diaphragm, means attached thereto for driving it, and a conical shaped member associated with said diaphragm remote from the apex thereof for damping vibrations imparted thereto, the base of said conical diaphragm being movable in response to vibrations imparted thereto,

30. In a loud speaker, a cone diaphragm supported in free access to air, a supporting ring for mounting said diaphragm, and a matching ring secured to the supporting ring, and having an open work projecting body, arranged to house but not contact with the cone diaphragm.

31. In a sound amplifying device, a diaphragm, said diaphragm being composed of a plurality of sections, said sections comprising a cone and a plurality of truncated cones, each of said sections adjoining an adjacent section along a commoh circumference, said sections being individually designed to have predetermined acoustic characteristics.

32. In a sound amplifying device, a diaphragm, said diaphragm being composed of a plurality of sections, said sections comprising a cone and a plurality of truncated cones, each of said sections adjoining an adjacent section along a common circumference, said sections being individually designed to have predetermined acoustic characteristics and each of said sections affording damping means for an adjacent section.

33. A loud speaker including a diaphragm com prising two concentric connected vibratory members formed of different material and having portions which do not overlap.

34. Aloud speaker including a diaphragm comprising two concentric connected vibratory members formed of different material and each having a portion free to vibrate without contact with the other, and means for simultaneously actuating the vibratory members.

35. A loud speaker comprising a cone diaphragm consisting of two concentric vibratory sections formed of different materials, one of said sections being of frusto-conical form and the other being in the shape of a cone closing the central smaller opening of the other section.

36. A loud speaker comprising a cone diaphragm consisting of two concentric vibratory sections of different sound reproducing charac teristics, one of said sections being of frusto-conical form, and the other being formed of thin metal in the shape of a cone closing the central smaller opening of the other section and secured to the adjacent edge thereof.

37. A loud speaker including a cone diaphragm comprising two sections, the outer one of which iai is frusto-conical and the inner one of which is conical, and closes the smaller open lend of the other section.

3S. A loud speaker including a cone diaphragm comprising two sections, the outer one of which is irusto-conical and the inner one oi which is conical and closes the smaller open end of the other section, and is formed of thin sheet metal.

RAYMOND L. WEGEL. 

